The present disclosure relates to techniques of a circuit board and a semiconductor element, in each of which solder bumps are formed for flip chip mounting, and a semiconductor device including a circuit board and a semiconductor element, and the like.
In recent years, a flip chip mounting method attracts attention as a mounting technique. This flip chip mounting method is a technique of mounting a semiconductor element, such as a semiconductor chip, on a substrate in a facedown state or mounting a semiconductor element on a semiconductor element in a facedown state (so-called “chip on chip”). Since having advantages, such as reduction in mounting area, as compared to a wire bonding method, recently, this flip chip mounting method has been used increasingly widely instead of the wire bonding method.
In the flip chip mounting method, for example, a terminal electrode called a bump is formed on a semiconductor element, and an electrode is formed on the substrate at a position corresponding to the bump on the semiconductor element. A solder bump is formed on the electrode on the substrate. In addition, the bump on the semiconductor and the electrode on the substrate are disposed to face each other and are fusion-joined to each other with the solder bump provided therebetween.
In general, as a method of forming a solder bump on an electrode, for example, a solder ball mounting method or a cream solder printing method may be used.
In addition, as a method of forming a solder bump on an electrode, for example, a technique disclosed in Japanese Unexamined Patent Application Publication No. 2000-77471 (paragraphs [0032] to [0042], and FIGS. 5 and 6) may be mentioned. A circuit board disclosed in Japanese Unexamined Patent Application Publication No. 2000-77471 has a conductor pattern having a wiring pattern and a connection pad. The width of the connection pad is formed wider than that of the wiring pattern. When a solder bump is formed, a solder powder is applied on the surface of the conductor pattern together with a flux and is then melted by heating. When the solder powder is melted, a phenomenon in which the solder gathers on the wide connection pad occurs, and the solder bump is formed on the connection pad. As described above, the solder bump is formed at a position exactly corresponding to that of a bump on a semiconductor element.